Objective To investigate the correlation and dose‑response relationship between serum uric acid (SUA) levels and metabolic associated fatty liver disease (MAFLD) as well as liver fat content among middle‑aged and elderly population.

Methods The cross‑sectional study was conducted with retrospective data for analysis. The clinical data of 1 607 subjects who underwent health check‑ups in two cities in Hubei Province from September 2022 to December 2024 were collected. There were 238 males and 1 369 females, aged 64 (59,68) years. Observation indicators: (1) SUA levels, liver fat content, prevalence of hyperuricemia and MAFLD in subjects and compari-sons of general data among subjects with different SUA levels; (2) correlation and dose-response relationship between SUA levels and MAFLD as well as liver fat content. Comparison of measure-ment data with normal distribution among multiple groups was conducted using the one-way analysis of variance, and Bonferroni‑corrected test was used for further pairwise comparison. Comparison of measurement data with skewed distribution among multiple groups was conducted using the Kruskal‑Wallis H test, and Bonferroni‑corrected Dunn′s test was used for further pairwise comparison. Comparison of count data among multiple groups was conducted using the chi‑square test, and Bonferroni‑corrected chi‑square test was used for further pairwise comparison. The restricted cubic spline (RCS) curve was used to analyze nonlinear trends. The Logistic regression model was used to assess the association between SUA and MAFLD. The multiple linear regression was used to assess the association between SUA and liver fat content.

Results (1) SUA levels, liver fat content, prevalence of hyperuricemia and MAFLD in subjects and comparisons of general data among subjects with different SUA levels: the SUA level of the 1 607 subjects was (304±80) μmol/L, and the liver fat content was 3.6% (2.7%,5.9%). Among the 1 607 subjects, 134 subjects had hyperuricemia, and 497 subjects had MAFLD. The 1 607 subjects were divided into quartile groups based on SUA levels, including Q1 group (SUA level <247 μmol/L) of 401 subjects, Q2 group (SUA level as ≥247 μmol/L and ≤296 μmol/L) of 402 subjects, Q3 group (SUA level as >296 μmol/L and ≤349 μmol/L) of 401 subjects, and Q4 group (SUA level >349 μmol/L) of 403 subjects, respectively. There were significant differences in gender, age, smoking, alcohol consumption, waist circumfe-rence, body mass index, body fat percentage, fasting blood glucose, glycated hemoglobin, triglycerides, total cholesterol, high‑density lipoprotein cholesterol, low-density lipoprotein cholesterol, creatinine, estimated glomerular filtration rate, systolic blood pressure, diastolic blood pressure, hypertension, diabetes, dyslipidemia, MAFLD, and liver fat content (χ²=105.46, H=16.09, χ²=66.32, 25.24, H=145.68, 112.25, 21.84, 16.22, 10.66, 76.86, F=3.05, H=70.54, 28.09, 250.74, 31.44, 27.97, 18.94, χ²=38.85, 10.21, 21.67, 108.02, H=130.12, P<0.05). (2) Correlation and dose‑response relationship between SUA levels and MAFLD as well as liver fat content: results of RCS curve showed that SUA levels had a nonlinear association with both MAFLD and liver fat content (P<0.05). Results of Logistic regression model analysis showed that after adjusting for gender, age, education level, annual household income per capita, marital status, residential area, smoking, alcohol consumption, physical activity level, sleep quality, daily total energy intake, and estimated glomerular filtration rate, compared with subjects in the Q1 group, the risk of developing MAFLD significantly increased among subjects in the Q2, Q3, and Q4 groups odds ratio (OR)=2.72, 4.28, 10.03, 95% confidence interval (CI) as 1.89‒3.92, 2.97‒6.17, 6.82‒14.75, P<0.05). Further analysis showed a dose‑response relationship between SUA levels and MAFLD. Per 60 μmol/L increasement in SUA level was associated with 84% increased risk of MAFLD (OR=1.84, 95%CI as 1.66‒2.03). Results of multiple linear regression analysis showed that after adjusting for gender, age, education level, annual household income per capita, marital status, residential area, smoking, alcohol consumption, physical activity level, sleep quality, daily total energy intake, and estimated glomerular filtration rate, compared with subjects in the Q1 group, the liver fat content was significant increased among subjects in the Q2, Q3, and Q4 groups (β=1.46, 2.08, 4.11, 95%CI as 0.84‒2.07, 1.45‒2.71, 3.45‒4.77, P<0.05). Further analysis showed a dose‑response relationship between SUA levels and liver fat content. Per 60 μmol/L increasement in SUA level was associated with 1.10% increased in liver fat content (β=1.10, 95%CI as 0.92‒1.28, P<0.05.

Conclusion For middle‑aged and elderly population, SUA levels exhibit a nonlinear association with both MAFLD and liver fat content, and as SUA levels increase, the risk of MAFLD and liver fat content in subjects also rise accordingly.